The invention has a particular application, particularly during interventions in critical situations and in unknown environments by safety workers such as fire fighters and emergency medical staff, police units or military forces.
In the state of the art, geolocation means identifying the location of a target, such as a targeted person or device, on a pre-established map by means of geographical coordinates. Such identification of location is achieved by means of firstly a GPS (Global Positioning System) receiver that locates the target considered exclusively outdoors and secondly a recorder and/or transmitter placed on the target. That recorder and/or transmitter can record and/or transmit respectively, in real time or with a time lag, the successive locations of the target as it moves, to the GPS receiver. Most often, the locations of the target are transmitted to the GPS receiver of a geolocation platform by means of a satellite communication system.
However, such a geolocation system, based on the use of a GPS receiver, cannot operate in a closed environment. That is because the signals sent by the transmitter located on the target cannot be detected by the GPS receiver. Further, the system uses a map, which is established previously, of the geographical environment in which the target is moving. Thus, it can be understood easily that the movement of a target in a closed environment, where the geographical configuration is unknown and of which there is no pre-established map, cannot be tracked by such a geolocation system.
A target can also be geolocated through a radio communication system, such as for instance a GSM (Global System for Mobile communications) system. Such GSM geolocation consists, firstly, in retrieving the identifiers of the GSM antennas to which the terminal is connected, and then, thanks to a database that connects the identifiers of cells to the geographical positions of antennas, the terminal is capable of determining its position and emitting an estimation of it.
However, the accuracy of GSM positioning can range from 200 meters to several kilometers, depending on whether the terminal is in an urban environment, with a high antenna density, or a rural environment.
Such inaccurate systems cannot be used to geolocate professionals, what is more public safety professionals, in closed environments.
All the same, the geolocation of public safety professionals during their work (for example fire brigades, police or emergency workers) is indispensable. That is because geolocation is carried out to enable the control room operators to know where the different safety workers are located, and thus ensure that their work can be done safely. Where applicable, control room operators can then take appropriate action and if required, transmit it directly to the workers in the field.
However, while working indoors, such as in a shopping centre, a factory, a car park or any other building, public safety professionals cannot use the aforementioned conventional geolocation system, because they need to work in a closed environment, which is, more importantly, an unknown environment. In the absence of relevant information about the topography of the place and the environmental conditions in which the worker is moving, it is impossible for the control platform operators to guide them optimally.
The safety of workers in critical situations depends on the quality of the assistance that the remote operator can give them. As a result, operations control operators need to have a complete image, in real time, of the critical situation in which the monitored worker is working, so that the said operator can react effectively and take the steps required to guide the worker as their work progresses.